This invention relates to an apparatus for guiding a threaded spindle in rotation, which spindle is used to ensure the translatory displacement of a mobile element connected to a threaded female piece engaged on this threaded spindle.
More specifically, the invention relates to an apparatus for guiding a threaded spindle in rotation, which spindle is used to ensure the translatory displacement of a mobile element connected to a threaded female piece engaged on this threaded spindle, which threaded spindle has a certain length and is connected, by one of its opposite ends, to a motor device for driving in rotation about its longitudinal axis in such a way as to allow the translatory displacement of the threaded female piece.
The invention applies more particularly, but not exclusively, to an apparatus for guiding in rotation a threaded spindle used to ensure, through a mechanical connection with the threaded female piece which it engages, the translatory displacement of a tool carriage on a machine tool, for example a lathe.
Especially on such machines, the carriage can be accidentally caused to collide with an obstacle, such as another carriage or slide, for example as a result of a wrong maneuver.
When it arises, such a blockage imposes particularly great mechanical stresses especially upon the threaded female piece connected to the carriage and upon the threaded spindle which controls the displacement of the said threaded female piece.
Known in order to limit the effects of such mechanical stresses is equipping the motor device for driving the threaded spindle in rotation about its longitudinal axis with a device for detection of an overload and of interruption in operation of the motor device if an overload is detected.
These devices have their advantages, but they effectively allow the stopping of the motor device; this is indisputable after great mechanical stresses have occurred, in particular between the threaded spindle and the threaded female piece.
One result which the invention aims to obtain is an apparatus for guiding in rotation a threaded spindle used to ensure the translatory displacement of a mobile element connected to a threaded female piece engaged on this threaded spindle which apparatus makes it possible to limit drastically the value of such mechanical stresses.
A number of machine tools make use of a plurality of assemblies each made up of a threaded spindle and a threaded female piece and more specifically constructions known by the name of ball screws.
These constructions are especially sensitive to axial stresses arising during the aforementioned blockages, i.e. these stresses can affect in particular their functioning to the point where they have to be replaced after having been stressed too much.
The invention has as its object a guiding apparatus of the aforementioned type, characterized in particular in that it comprises at least one device for elastic absorption of a force which, oriented axially with respect to the threaded spindle and toward either one of its opposite ends, arises between this threaded spindle and the threaded female piece and the value of which is considered likely to distort in particular the surfaces along which the threaded spindle and the threaded female piece cooperate.
The invention will be better understood from reading the description which follows, given by way of non-limiting example, with reference to the attached drawing which schematically represents an apparatus for guiding a threaded spindle in rotation, according to the invention, seen in a section along a longitudinal plane.